what spark plug to use
 

i have a sbc with vortec heads what is a good plug to start with and what # plug . thanks for your help.

I like the NGK plugs! JMO
I think NGK TR5 is stock replacement for gas. I think they have TR55 and TR6 for different heat ranges. May give you something to start with.
Some of the other fellows could help better on the small block stuff, I run 8's in a gas BBC

I use NGK plugs too.